Micro-Electro Mechanical Systems (MEMS), which are sometimes called micromechanical devices or micromachines, are three-dimensional objects having one or more dimensions ranging from microns to millimeters in size. The devices are generally fabricated utilizing semiconductor processing techniques, such as lithographic technologies.
Generating effective actuation in a fluidic environment is challenging, as standard MEMS actuation methods are generally ineffective in this environment. For example, electrostatic actuators, such as an electro-static comb drive, will not function with a conducting dielectric, such as water. Thermal actuators, such as thermal bimorph actuators, are of limited value, as the boiling point of the surrounding fluid limits the thermal range of the device. Piezoelectric actuators have been used to some effect in micro-fluidic devices. However, these actuators have limited actuation range and are difficult to fabricate.
It would be highly desirable to generate actuation in a fluidic environment for applications such as flow regulation, stirring, positioning of mirrors within a flow stream, moving cells or biological samples, etc. It would be highly desirable to provide an actuator with large actuation ranges, which requires minimal energy to generate displacement, which requires little or no energy to maintain a given displacement, and which requires minimal energy to return to its initial configuration. Ideally, such an actuator could be constructed using standard MEMS fabrication techniques.